Drafting machine



Aug; 15, 1950 c. H. LITTLE 2,519,143

7 DRAFTING MACHINE Filed Feb. 25, 1946 3' Shee ts-Sheet 1 llllllllv v INVENTOR.

c. H. LITTLE DRAFTING 11110111111:

Aug. 15, 1950 5 Sheets-Sheet 2 Filed Feb. 25, 1946 IN VEN TOR.

147701NEY5 1950 c. H. LITTLE 2,519,143

DRAFTING MACHINE drawing board;

Patented Aug. 15, 1950 OFFICE f BRAFEBING mom Charles Hubbard Little, Cleveland, Dhiq, assignor 'to Universal Drafting Machine Corporation 7: Elevdlaznd, *Ohima corporation 'of 'Ohio Application February 25,v1 946,"Serial No. 649,861

'l ll Clailns.

4 frfhepresentfinvention relates Parana h gh mechanisms or armsgprovided with counter- *poise means and,;more specifically to a drafting mach'i necompfising a parallel motion arm of the'wheeland band type comprising counter- ;poise mechanism for part or all of the aim.

One of the principal objects of'the invention "i'sfl the provision of a;novel and improved drafting'madhine of the wheel and band type, having 'the band's and'wheels completely enclosed, which tion is the prov ifion of'a novel and improved dral ting' machine of the wheel and band type comprising improved means torcounterbalanc- 7 'ing the weight of-the arm when "the machine is used on'an inclined'dmawing surface.

The invention resides in certain constructions and combinations and arrangements of parts and ifmrther oibjectsiand advantages will be apparent skilled in the art to the invention the following description of the prefielmed embodiment described with reference to the acconmmyinsdrawinesiomdng "a, part of thiefzspezcificaltioh in :similaar reference ehametersidesignateeorresponding narts andiin which" LEFig. lissamlanwiewofawaiting machine-emzbody mg the-present invention, =attached to a Fig. 2 is an enlarged "plan view of the anchor ortion or the drafting maehinewshown in Fig, ,1; Fig. 3 is a View similar to Fig. 2 but showing thepartsina difierent operative position;

" 4 4'16 a seotional with portions elevation; approximately on the line 4--4' of Fig.

.2sand V I V Fig. 5 is a sectional View, with portions in releva i n, approximately on the lined-5 of Fig. i. The drafting machine shown in the drawings comprises a two-section, parallel motion mechor arm of the wheel and band type having one end detachably connected to :a drawing board and the other or tree end provided with rnlersor other instruments which it is desired to: moveabout the -dramng board or the like.

narallel motion mechanism or arm,=comprises two aneularly movable; sections each oom- ,prisin va pair otwhecls of equal diameter en- ,section -matnprises wheels -].0,,

H .=encircled an endless band 12 and held in spaced relationby an enpandible strut A operatively connected thereto .for relative rotation with respect to. the

strut in a manner hereinafter described.

The upper wheel Hlis formed integral .a

member 14 ,pivotally connected, .as by pivots L5,

lithe latter of which is adjustable, to a bracket member .IJ forming a part of the anchor assembly, which ,braoket member is adapted .to engage over the upper edge. of the drawing board 13 and be .detachablyfixed thereto .by a clampsorew 18 located underneath the .drawingboard and having threaded engagement in. .a suitably anne aperture in thelower end of projecting arm 20 formed integral with ethe'anchor bracket. fIlae upper end of 'the clamp screw L8 vis provided with a board-engaging member 2'! connected thereto :by looseqjoints which-mermit the ,mem-

(bers to .set -,pronerly against the underside of the board. The trout side of the member is'proyided lwithan adjustable stop 2.2 threaded onto the lower end of again 223 fixed in the member 1.4, which stop adapted to engage .a flange or plate-like proiection 24 on the brackelt l1 immediatel above the drawing hoard .B. The-strut A comprises yoke or yoke members .25., .25 located lat-the anchor and elbow ends. Ire- ,spectively of the anchor section of the arm and connected togetherand held in spaced relation by tnbularside .portionsor members 2]., 2'8..- fIEhe anchor yoke .25 is rotatably -.oonnec'ted by antifri'ction bearings $0,, 31 .to .a headed; bolt or pivot member 32 fixedly securedinaboss 3.3 on a web 34 within the member A 4 .by jamnuts 35, '36 The b01t -3i2torms .avotf or the strut A. Ihe yoke member 25 is provided with .a downwardly extending boss 3.! on lower side having a central aperture 38 'therethrough .sowformed as to oroyide .aninwardly projecting annular flange that the lower end of theboss, The head 41 of the Y The yoke 26 ofthe anchor strut .A located at ciqele d by-aflexible bflnd, e'lheupper oranohor M elbow of the ann' is pivotally connected'to the wheel i i for rotation about the center of the wheel as an aXis by a bolt 45 similar to the bolt 32, previously referred to. The wheel H is formed integral and concentric with the wheel 46 of the strut C of the protractor section of the arm and the two wheels are fixed t the pin 45. The two yoke members 26, 41, the latter being the yoke member of the protractor strut C at the elbow of the arm, are pivotally connected with respect to each other and the wheel assembly comprising the wheels ll, 46 and the bolt '25 by anti-friction bearings 59, respectively, in a manner similar to that in which the yoke 25 is rotatably connected to the [wheel Ill. The bearings 50, 5| are located in apertures 52, 53 'in-tl'ie yoke members 26, ll, respectively, similar to the aperture 38 in the yoke member 25. The apertures 52, 53 are provided with removable covers 54, 55 respectively, similar to the cover 3 for the aperture 38.

The protractor section of the parallel motion ,arm, that is, the section comprising the pro- I tractor head and rulers, etc., is similar in construction to the anchor section already described and comprises in additionto the wheel 46, pre- ,viously mentioned, a wheel 56 of equal diameter 'and held in spaced relation withrespect to the wheel 45 by the strut 0 similar in construction to the strut A. The wheels 46, 56 are encircled by anendless band 51' similar to the band I 2. In

the embodiment shown, the wheel 56 located at the free end of the paral el motion arm forms a part of the instrument head, designated generally as D, or, conversely, the instrument head is a part of the parallel motion arm'. Alterna- 'tively, the instrument head couldbe constructed as'a se arate unit and detachably secured to the wheel 56.

The struts A, C are expandible or adjustable in len th and se arable intermediate their ends to j facilitate assembly and replacement ofthe bands 312,1 5! and for the purpose of tensioning the same, etc.

7 e The tubular side members of the struts and the flexible bands are preferablysimilar in construction to those disclosed in a co- I pending application of Charles H. Little et al.,

fierial No. 631.3391. fi ed November 28, 1945, en-

.titld Drafting Machine and are not herein 'shown and described in detail. Suflice it to say that the tubular side portions proper of the struts are discontinuous intermediate their [ends and have their adiacent endsconnected together by tubular-like'nut members 58 rotatab e in one direction to expand thestrut andtense the band and inthe opposite direction to release the tension on the band and loos'en'the nut so that it can '1 be moved longitudinally of the strut to expose a portion of the band. The bands shown are The instrument head D is not'herein shown 'and'described in detail and may be of any desired construction. Preferably it is similar to that disclosed and claimed in my copending application' Serial No. 745.300, filed May 3, 19.4.7,

entitled Drafting Machine, to which reference is made for a complete disclosure thereof. For

thepresent purpose, it is sufiicient to say that the instrument head comprises a ruler assembly 7 ,including a hand grasp 60, a member s! forming one'element of'a protractor proper, one or "more rulers 62," B3 detachably secured to a ruler or chuck arm 64, and means for selectively clamping the assembly to the wheel member 56 including a clamp and indexing mechanism operated by a thumb piece 66. The instrument head also comprises a normally stationary protractor element 6! which cooperates with the rotatable element to indicate the angular position of the rulers with respect toabase line.

The present invention contemplates the provision of individual counterpoise means for each section of the parallel motion arm, which counterpoise means is simple in construction, inexpensive to manufacture, will not be bulky and ungainly in appearance, and which can or cannot bereadily incorporated in the drafting machine, as desired. Each of the counterpoise mechanisms comprises a counterpoise force producing anchor section of the arm is shown and described herein in detail. Those parts of the counterpoise mechanism for the protractor section of the arm which are shown in the drawings are designated by the reference character used to designate the corresponding part in the mechanism-for the anchor section with a prime mark afiixed thereto.

The head 4| of the bolt 32 is provided with an eccentric pin 10 projecting from the top more or less in the nature of a crank pin, the crosssection of which pin is preferably elliptical in shape or. approximately so with its major axis genera ly parallel to'the upper edge of the drawing board or generally normal to a vertical plane through the axis of rotation of the strutwhen attached to an inclined drawing board or table. The pin H1 constitutes a cam at or adjacent to one end of the pivot 32, which cam is engaged by one end of a compositeplunger or cam follower E slidably supported for linear movement by a tubular bushing H in an aperture 12 in the yoke 25. The aperture 12'is located in the longitudinal centerline of the. strut and the centerline of the aperture intersects the axis of rotation of the strut. The plunger E is continuously urged in a direction to engagethe pin 10 by a compression spring 13 located within an adiustahle tubular assembly F detachably connected to the yoke 25. v

The composite plunger or cam follower E interposed between the crank 'pin or cam 10- and the counterpoise spring 13 comprises a body member 14 slidably supported within the bushing?! and a'headed member 15 provided with a tapered shank by virtue of which it is fixedly retained in the left-hand end of the member 14,

see Fig. 4. The head of the member 15 is pro- "vided with a cam-engagingflat surface '15 of considerable length which engages the side of the crank pin or cam 10. The opposite or righthand end of themember 14 has a headed pin-like member 11 rotatably secured therein through the medium of a reduced shank portion rotatably supported in a suitable aperture in the end of the member 14. The head of the member]! engages one end of the counterpoise spring 13. The

ropposite end orthe spring abuts; the closed: end or a tubular member 18 oi the assembly F;

tubular assembly- E comprises two teleascnped tubes [8: and 81! threaded engagement. with each other so that the efiective length or the assembly can be varied by rotating". the outer tube- 18 relative to the tube so. The left-hand end of the inner tube aflrisireducedand provided threads adapted to. cooperate with threads in the right-hand end orthe aperture B2. The construction is such that when the drafting machine. is intended to be used. on a. horizontal board, the counterpoise means be readily removed by merely unscrewing the tubular asembly F from the yoke .25, withdrawmg the member M through thec'righthand end. of the aperture 12,. and removing the headed member i through the'opening. normally closed by the cover 43 The parts are so proportioned that this can be readily accomplished.

If desired, the machine can be manufactured,

omitting" the counterpoise mechanism, which connterpoise mechanism may becsupplied at any future; time. In the event the counterpoise mechanism is: not. desired, a pin similar tothe pin 32 but omitting the crank pin may be. substituted for the pin 32. The exposedend of the aperture 12 may. be closed by a suitableplug.

Thedirection of the. counterpoising force pro- 'idnced by the counterpoise force producing spring 13 will be parallel to the direction of linear move- -ment; or the plunger or cam follower .E and normal to the point of contact of; the member 15 with the pin it and will be applied to the supporting member or wheel at an increasingly greater distance from the center of rotation of the strut as: the strut is rotated in either directioni from its normal vertical position shown in Fig; 2.. The fact that the counterpoising. force produced isalways parallel or generally parallel to-the direction of movement of the cam follower,

simplifies the construction and increases the accuracy of thecounterbalance. Themaximum distance from center obtained whenthe anchor "section of the arm is substantiallyparallel with the upper edge of the drawing board, assuming that the. upper edge. "ofthe drawing board is in a horizontal plane when the board is in a vertical position. The positions assumed by the various 7 parts when the anchor section is rotated about I 45 to the'left of the vertical or normal position are shown in Fig- 3. 1

As previously stated, the cross-sectional shape of the crank pin or cam mis substantially ellipt'ical: so as to compensate for such things as change in spring pressure incident to a change spring length, etc. It will be readily apparent "that by changing the shape cf the crank pin or the necessity of making distinctly different ma-.

chines for use on horizontal. and vertical boards.

The present machine can be supplied with or without the counterpoise mechanism without ma- 7 terially affecting theappearance of the machine.

" A machine originally supplied; without the counterpoise mechanism can be readil converted for use with inclined boards bymerely adding. the counterpoise mechanism, which is. an extremely simple matter especially if the original, machine included a. boltsimilar to the bolt 32.

While the. preferred embodiment of the inventi'on. has been described in. considerable detail, I'do not wish to be limited to. the particular con struct'ion shown which may be. varied within the scope or this invention and it is my intention to hereby cover all adaptations, modifications and uses. thereof which come within the. practicev of those skilled in the art to which the invention relates and within the scope of the appended claims.

Having thus described my invention, I claim 1. In a drafting machine or like device, a pair of wheels, a. strut; pivotally connected with re spect to said wheels for rotation about axes concentric therewith, a flexible band encircling.- said wheels, means for Supporting one of said wheels, a cam eccentrically fixed with respect to said supported Wheel. said cam being generally elliptical in shape and having its minor axis substantially in th plane of the centers of the cam and said supported wheel, a cam follower slidably supported in said strut and adapted to engage said cam, and counterpoise' spring means carried by said strut continuously urging said cam follower into engagement with said earn.

2. In a drafting machine or like device, .a pair of wheels, a strut pivotally connected with respect to said wheelsfor rotation about axes concentric therewith, a flexible band encircling said wheels, means for supporting one of said wheels, a pin eccentri'cally fixed with respect to said supported wheel. said pin being generally elliptical in shape and positioned with its major axis generally normal to a vertical plane through the axis of relative rotation between the supported wheel and strut when the drafting machine is attached to an inclined drawing board or table, a member slidabl supported in said strut and adapted to engage said pin, and counterpoise' spring means carried by said strut continuously urging said member :into en agement with said pin.

3. In a draftingmachine or like device, a pair of wheels, a strut pivotally connected with respect to said wheels for rotation about axes concentric therewith, a flexible band encircling said wheels, means for sup orting one of said wheels, a cam eccentrically fixed with respect to said supported wheel, said cam being generally elliptical in shape and having its .minor axis substantially in the, plane of the centers of the cam and said supported wheel, a cam follower having an elongated transversely extendingsurface adjacent to one end adapted to engage said cam, means for slidably supporting said cam follower in said strut for linear movement toward and from said cam, and counterpoise spring means carried by said strut continuously urging said cam follower into engagement with said cam.

4. In a drafting machine or like device, a pair of wheels, a strut pivotally connected with respect to said wheels for rotation about axes concentric therewith, a flexible band encircling said wheels, means for supporting one of said wheels, a cam ecccntrically fixed with respect to said supported wheel, said cam being generally elliptical in shape and having its minor axis substantially in the plane of the centers of the cam and said supported wheel, a cam follower slidably supported, in said strut, a tubular member detachably connected to said strut, and counterpoise spring means within said tubular member continuously urging said member into engagement with said pin.

5. In a drafting machine or like device, a pair of wheels, a strut pivotally connected with respect to said wheels for rotation about axes concentric therewith, a flexible band encircling said wheels, means for supporting one of said wheels, a cam eccentrically fixed with respect to said supported wheel, said cam being generally elliptical in shape and having its minor axis substantially in the plane of the centers of the cam and said supported wheel, a cam follower having an elongated transversely extending surface adjacent to one end adapted to engage said cam, means for slidably supporting said cam follower in said strut for linear movement toward and from said cam, a tubular assembly detachably connected to said strut, counterpoise spring means within said tubular assembly continuously urging said member, into engagement with said pin, and means for adjusting the force of said counterpoise spring.

6. In a drafting machine or like device, two

members pivoted with respect to each other, a cam fixed with respect to one of said members and eccentric to the pivotal axes therebetween, a cam follower movably supported by the other of said members and adapted to engage said cam,

said cam being generally elliptical in shape and having its minor axis substantially in the plane of the centers of the cam and th pivot, and counterpoise spring means continuously urging said cam follower into engagement with said cam.

'7. In a drafting machine or like device, a wheel member, a strut member pivotally supported with respect to said wheel member for rotation about an axis concentric with said wheel member, a flexible band encircling said wheel member, a cam fixed with respect to one of said members and eccentric to said axis, a cam follower mov- V ably supported by the other of said members and adapted to engage said cam,lsaid cam being generally elliptical in shape and having its minor axis substantially in the plane of the centers of the cam and the wheel member, and counterpoise spring means continuously urging said cam follower into engagement with said cam.

8. In a drafting machine or like device, two

members pivoted with respect to each other, a cam fixed with respect to one of said members and eccentric with respect to the pivotal axis therebetween, said cam being generally elliptical in shape and having its minor axis substantially in the plane of the center of the cam and said pivotal axis, a cam follower supported by the other of said members for linear movement toward and from said cam, and counterpoise spring means continuously urging said cam follower into engagement with said cam, said cam follower having an elongated transversely extending surface adapted to engage said cam whereby the counterpoising force of said spring is always exerted parallel to the direction of linear movement of said cam follower.

9. In a drafting machine or like device, a wheel member, a strut member pivotally supported with respect to said wheel member for rotation about an axis concentric therewith, a flexible band encircling said wheel member, a cam fixed with respect to one of said members and eccentric to said axis, said cam being generally elliptical in shape and having its minor axis substantially in the plane passing perpendicularly through the center of the cam and the axis of said one member, a cam follower supported by the other of said members for linear movement toward and from said cam, and counterpoise spring means carried by the other of said members continuously urging said cam follower into engagement with said cam, said cam follower having an elongated transversely extending surface adapted to engage said cam whereby the counterpoising force of said spring is always exerted parallel to the direction of linear movement of said cam follower.

10. In a drafting machine or like device, a wheel member, a strut member, means including a pivot fixed with respect to said wheel member for pivotally connecting said members for relative rotation about the center of said wheel member as an axis, a flexible band encircling said wheel member, a cam at one end of said pivot and eccentric thereto, said cam being generally elliptical in shape and having its minor axis substantially in the plane of the centers of the cam and the pivot, a cam follower movably supported by said strut member for linear movement toward and from said cam, said cam follower having a plane surface normal to the direction of the linear movement of the cam follower adapted to engage said cam, and counterpoise spring means carried by said strut continually urging said cam follower into engagement with said cam.

CHARLES HUBBARD LITTLE.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS 

